[Zope] REQUEST Variables and Caching

[Dyyryath]

Can anyone here give me a quick explanation of how the 'REQUEST
variables' field works in the RAM Cache Manager properties? I've
looked and all I can find is:

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This information is used to store the cached copy of a page.
This is an advanced feature, for now, you can leave this set to just
"AUTHENTICATED_USER".
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I'm trying to ensure that the cache manager only caches things for
users who are NOT logged in.